Fabrication and characterization of TiO₂ nanotube arrays on Ti membrane enlarged by anodic oxidation

TiO₂ nanotube arrays have attracted a great deal of attention as photocatalytic and photoelectrode materials due to their large surface area, low cost and easy fabrication. Highly ordered TiO₂ nanotube arrays for the photoelectrodes in dye-sensitized solar cells have been fabricated from Ti foil. However, the TiO₂ nanotube arrays from Ti foil were not effective for the photocatalytic materials, because it had only one plane for the photocatalytic reaction. We have fabricated the TiO₂ nanotube arrays from macroporous Ti metal membrane by anodic oxidation and tried to scale it up. Various factors were controlled to obtain the optimal microstructure of the TiO₂ nanotube arrays on the surface of macroporous Ti metallic membrane. Microstructure and phase were studied by SEM and XRD, respectively. Temperature was a very important factor in anodic oxidation of large surface area. 10 μm thick TiO₂ nanotube arrays on Ti metallic membrane having a large surface area were fabricated and some factors for scaling-up were discussed.